I always try to give people the benefit of the doubt. Maybe the sales person was not trying to be rude. She grossly misjudged your response. Perhaps she was just trying to make conversation. I've had employees and the store owner make comments about how often I visit the store. Usually it is to see if I have a project in mind or to make conversation, and never to judge. These brief conversations made me feel like I wasn't just another customer. If a comment bothers you tell the clerk right away. How else will she know that it bothers you. Just my 2 cents.